RE: Attacking Domain Keys

> As is the implementation of any other algorithm.  RSA 
> signature validation is a very CPU-intensive algorithm that 
> unfairly burdens the recipient. HMAC-SHA1 signatures are much 
> faster, and you can optimize both to your heart's content and 
> still come up with the same result.
How do trolls perform the necessary key distribution?

If you understood what HMAC is then you would know why it is completely
impractical for this application, the authentication key must be shared
between sender and receiver.